Field of the Invention
The present invention concerns an apparatus for bending elongated metal products, such as for example metal bars, round pieces, wire or other, both pre-cut or fed from a roll. In particular, the apparatus according to the present invention is applied to make stirrups, or other reinforcement elements for the building trade, having a three dimension conformation, that is, with at least a portion bent back on an orthogonal plane, or in any case angled, with respect to the normal bending plane of the other portions.
The present invention also concerns a method for bending elongated metal products in order to obtain stirrups with a three dimension conformation.
Description of Related Art
Bending machines are known, also by the name of stirrup-making machines, which are configured to bend a metal bar, round piece, wire or other similar metal product, in order to make stirrups for reinforcement cages.
One example of these machines is disclosed in U.S. Pat. No. 1,836,502.
Two types of reinforcement stirrup are substantially known, that is, the so-called two-dimensional stirrups and the so-called three-dimensional stirrups, both able to be disposed in succession with respect to each other and connected by longitudinal bars so as to define the reinforcement cage.
Two-dimensional stirrups are more widespread on the market and define the transverse profile of the reinforcement cage substantially on the same bending plane.
Three-dimensional stirrups have their shape defined on a first bending plane coinciding with the feed plane and at least a portion, or segment, angled with respect to the first bending plane, for example with the function of spacer, or reference element, with respect to another stirrup or another existing structure.
This type of stirrup is made by means of automatic bending machines which provide, as well as a drawing station and a shearing station, a first bending station which makes the bends on the first bending plane, in order to define the two-dimensional shaping of the stirrup, and a distinct and subsequent second bending station which makes the bends in order to define the portions or segments angled with respect to the first bending plane.
In general, the first bending station essentially consists of at least a bending support, or mandrel, generally in the shape of a disc, rotating around a normally central axis, defining the first bending plane and provided centrally with a contrasting pin. On one spoke of the mandrel a bending element is provided, substantially coplanar to the contrasting pin.
The bending element can be rotated both in a clockwise direction and in an anti-clockwise direction, around the contrasting pin, so that the elongated metal object is shaped by plastic deformation around the contrasting pin, in one direction or the other.
In the same way, the second bending station, normally distanced and autonomous with respect to the first bending station, provides a contrasting member disposed at a distance from the feed plane of the bar, in order to allow the elongated metal element to be bent to be positioned between it and the feed plane, and a movable bending element exiting from the feed plane in order to intercept a segment of the elongated metal element, so that the elongated metal element is shaped by plastic deformation around the contrasting member.
This type of known bending machine, providing two distinct bending stations, needs a double line of command and control, both mechanical and electronic, in order to guarantee the management and operating coordination of the two bending stations.
This management need entails an increase in production times and costs of the apparatus, as well as maintenance times and costs.
Moreover, by providing two distinct stations, the number of mechanical components which participate in the individual movements is also high, and the apparatus is bulkier than traditional machines, with consequent increases in installation bulk, and the bending precision can also be compromised.